Refrigerant distribution improvement in parallell flow heat exchanger manifolds

Abstract

A method and apparatus are presented to ensure adequate distribution of a two-phase refrigerant flowing through a plurality of heat transfer tubes of a parallel flow heat exchanger in a generally parallel manner. In several embodiments of this invention, predominantly single-phase refrigerant (liquid for condensers and vapor for evaporators) is tapped and delivered downstream to a location where a predominantly single-phase refrigerant phase is already present, bypassing at least some of the heat transfer tubes. In this manner, the remaining single-phase refrigerant (vapor for condensers and liquid for evaporators) flowing through the heat exchanger core is uniformly distributed amongst a plurality of heat transfer tubes in the next downstream pass.

1 . A refrigerant system comprising:
 a compressor for delivering a compressed refrigerant to a condenser, refrigerant from said condenser passing through an expansion device, and from said expansion device through an evaporator, and from said evaporator being returned to said compressor; and   at least one of said condenser and said evaporator having a plurality of heat transfer tubes which pass a refrigerant downstream in a generally parallel manner; and   
     at least one location within said at least one said condenser and said evaporator being likely to receive separated vapor and liquid phases of refrigerant mixture as the refrigerant flows through the plurality of heat transfer tubes, and at least a portion of one of a separated liquid and vapor phase being tapped from said location and delivered to a downstream location bypassing at least some of the heat transfer tubes to improve distribution of a remaining refrigerant flowing through the bypassed heat transfer tubes that are in direct fluid communication with this location. 
   
   
       2 . The refrigerant system as set forth in  claim 1 , wherein said heat exchanger is a condenser and said tapped refrigerant is liquid. 
   
   
       3 . The refrigerant system as set forth in  claim 1 , wherein said heat exchanger is an evaporator and said tapped refrigerant is vapor. 
   
   
       4 . The refrigerant system as set forth in  claim 1 , wherein said at least one of said condenser and said evaporator has at least one manifold structure in fluid communication with said plurality of heat transfer tubes, said at least one manifold structure being provided with at least one separation member providing at least two chambers within said at least one manifold structure, and at least one of said chambers being said tap location. 
   
   
       5 . The refrigerant system as set forth in  claim 4 , wherein said separation member is one of a separation plate, a check valve, a float valve, a solenoid valve, an orifice with a liquid seal and a combination thereof. 
   
   
       6 . The refrigerant system as set forth in  claim 1 , wherein said at least one of said condenser and said evaporator has at least one manifold structure in fluid communication with said plurality of heat transfer tubes, said at least one manifold structure being provided with at least one separation member providing at least two chambers within said at least one manifold structure, and at least one of said chambers being said downstream location. 
   
   
       7 . The refrigerant system as set forth in  claim 1 , wherein said at least one of said condenser and said evaporator has an outlet refrigerant tube and said outlet refrigerant tube being said downstream location. 
   
   
       8 . The refrigerant system as set forth in  claim 1 , wherein said separated refrigerant is at least partially carried by a bypass line. 
   
   
       9 . The refrigerant system as set forth in  claim 8 , wherein said bypass line has at least one of external and internal heat transfer enhancement elements. 
   
   
       10 . The refrigerant system as set forth in  claim 8 , wherein said bypass line associated with at least one of said condenser and said evaporator is positioned in the airflow path moving over at least one of said condenser and said evaporator. 
   
   
       11 . The refrigerant system as set forth in  claim 10 , wherein said bypass line associated with at least one of said condenser and said evaporator is positioned upstream at least one of said condenser and said evaporator, in relation to the airflow. 
   
   
       12 . The refrigerant system as set forth in  claim 1 , wherein a flow control device allows said tapped refrigerant flow to be controlled. 
   
   
       13 . The refrigerant system as set forth in  claim 1 , wherein said plurality of heat transfer tubes have external heat transfer fins in heat transfer communication with said heat transfer tubes. 
   
   
       14 . The refrigerant system as set forth in  claim 1 , wherein each of said plurality of heat transfer tubes have a plurality of small parallel internal channels carrying refrigerant in parallel paths within said heat transfer tubes. 
   
   
       15 . The refrigerant system as set forth in  claim 14 , wherein said parallel internal channels create a microchannel heat transfer tube or a minichannel heat transfer tube. 
   
   
       16 . The refrigerant system as set forth in  claim 14 , wherein said parallel internal channels have at least one of circular, rectangular, trapezoidal or triangular configuration. 
   
   
       17 . The refrigerant system as set forth in  claim 1 , wherein there are multiple tap locations. 
   
   
       18 . The refrigerant system as set forth in  claim 1 , wherein there are multiple downstream locations. 
   
   
       19 . A method of operating a refrigerant system comprising the steps of:
 (1) providing a compressor for delivering a compressed refrigerant to a condenser, refrigerant from said condenser passing through an expansion device, and from said expansion device through an evaporator, and from said evaporator being returned to said compressor; and   (2) providing at least one of said condenser and said evaporator having a plurality of heat transfer tubes which pass a refrigerant downstream in a generally parallel mariner; and   (3) identifying at least one location within said at least one said condenser and said evaporator likely to receive separated vapor and liquid phases of refrigerant mixture as the refrigerant flows through the plurality of heat transfer tubes, and at least a portion of one of a separated liquid and vapor phase being tapped from said location and delivered to a downstream location bypassing at least some of the heat transfer tubes to improve distribution of a remaining refrigerant flowing through the bypassed heat transfer tubes that are in direct fluid communication with this location.   
   
   
       20 . The method as set forth in  claim 19 , wherein said at least one of said condenser and said evaporator has at least one manifold structure in fluid communication with said plurality of heat transfer tubes, said at least one manifold structure being provided with at least one separation member providing at least two chambers within said at least one manifold structure, and at least one of said chambers being said tap location. 
   
   
       21 - 30 . (canceled)